docs: def get_saml_slos(cls, logout_request):
          """returns saml logout ticket info"""
          try:
              root = etree.fromstring(logout_request)
              return root.xpath(
                  "//samlp:SessionIndex",
                  namespaces={'samlp': "urn:oasis:names:tc:SAML:2.0:protocol"})
          except etree.XMLSyntaxError:
              return None